I've had this happen more times than I can count, and it never stops being infuriating.
Once I was on a MUP, fairly congested, walkers, joggers and bikers. A group of people was coming from the other way, on the correct side, but then there's this tiny woman jogging to her left headed right towards me. I couldn't pass between her and the group so I just stopped and told her she needed to jog on the other side, she stopped and started arguing. We were literally - as in actually - standing in front of a sign that stated 'KEEP RIGHT, WARN WHEN PASSING' with a picture of a bike following a jogger following a walker on it. I stood there pointing at it and she argued again some incomprehensible gibberish. Despite this, the jogger insisted I move out of her way. After about 30 long seconds of a standoff, she finally went FURTHER to the left around me into the grass. Strange.
Earbuds are the bane of mankind in MHO. I have followed and had people nearly walk into me just completely zoned out, I'e even made eye contact with a few and yet they still zombie jog or walk right into me. Luckily I've always been stopped. If people insist on wearing these then the need to leave one out or at least keep the volume below 11. I got stuck behind a jogger that had his buds so loud I could hear the music from 5' away. He weaved back and forth on the MUP and despite me literally screaming at him I was going to pass, he was completely unaware I was there. I finally thought he settled into the right side, so I thought and I tried to pass slowly, still yelling I was on his left, he suddenly darted left and ran right right into me. Thankfully we both stopped and no one went down. He popped a bud out and the music was just screaming loud. I admit, I got a bt pissed and yelled that I had been following him for the last 200 feet, and he should give us a break and turn his music down or keep one bud out. He was apologetic, but popped it right back in and was on his way. It could have ended up a lot worse. There was some areas we passed that had a steep bank and someone could have ended up going down it.
It's gonna happen, people are stupid beasts at times, including cyclists. As irritating as it is I'd rather take my chances on a MUP then a street with heavy traffic.